1. Field of the Invention
The present invention relates to an image pick-up device and, more particularly, an image pick-up device and system wherein the image pick-up device comprises an image sensor having a plurality of photocells arranged along rows and columns thereof and a storage for storing signals from the image sensor.
2. Description of the Prior Art
The image pick-up device of the type described above is well-known as a frame transfer image pick-up device. Conventionally, in the frame transfer image pick-up device, the number of vertically arranged photocells (the number of rows of the image sensor) is 245, nearly equal to half the 525 horizontal scanning lines for one frame in the NTSC color system. The photocells can store signals corresponding to data for 245 horizontal scanning lines (i.e., one-field data) since they have both photosensitivity and data transfer functions. After the signals for one field are read out, the effective photosensitive region of the photocells is shifted for image pick-up, and then the subsequent signals for a different field are read out, thereby performing interlaced scanning to obtain an interlaced frame image.
The above system is most suitable for an interlaced scanning television system since an image with a high resolution can be obtained in spite of a small number of photocells.
However, the size and sensitivity of the photocell are limited. As a result, the image pick-up sensitivity of the photosensor is limited. Although various attempts have been conventionally made to improve the sensitivity of the image pick-up device, an image pick-up device with good resolution has not been proposed.
In the image pick-up systems such as illustrated in the copending applications Ser. No. 390,055 filed on June 18, 1982 by NOBUYOSHI TANAKA et al and Ser. No. 390,054 filed on June 18, 1982 by NOBUYOSHI TANAKA et al and assigned to the same assignee, signals generated from a plural number (e.g., 2 rows) of rows in an image sensor are added during the transfer from the image sensor to a storage and stored in the storage. By reading out the sum signals from the storage, an effective image pick-up sensitivity of the photosensor is improved. It is also possible to perform 2:1 interlacing by changing the rows to be added together between the first and second fields. In an image pick-up system according to a preferred embodiment to be described later, the addition of row signals is performed at the first row of the storage (i.e., the row of the storage which is adjacent to the image sensor).